The nitrotoluenes are chemicals used in
dyes, agricultural products,
pharmaceuticals and
explosives. In the present studies, the toxicology and immunotoxicity of
meta-nitrotoluene (
m-nitrotoluene) were evaluated. Mice, exposed to
m-nitrotoluene at dose levels of 200, 400 and 600 mg/kg/
body weight for 2 weeks by gastric gavage, gained
body weight over the treatment period to a slightly greater extent than the control groups. Of the selected organs weighed, the liver and kidney of mice exposed to
m-nitrotoluene were increased in weight while the thymus weight was decreased. The liver of mice exposed to
m-nitrotoluene, but not
ortho-nitrotoluene, showed slight to moderate swelling of the hepatocytes adjacent to the central veins. The hepatocyte swelling appeared to be reversible and there was no evidence of
necrosis. The hematology and serum chemistries examined were unaffected by
m-nitrotoluene exposure although there were modest decreases in the percentage of polymorphonuclear leukocytes and eosinophils in differential blood counts. Bone marrow cellularity and the number of CFU/M and CFU/GM were unaffected by
m-nitrotoluene exposure.
m-Nitrotoluene suppressed the
IgM response to sRBC and the DHR response to KLH. There was a slight (8%) decrease in the percentage of B lymphocytes in the spleen. The response to the T cell
mitogens was suppressed by as much as 39%. Fc-mediated adherence and phagocytosis of chicken erythrocytes and NK cell activity were increased dose dependently in mice exposed to
m-nitrotoluene. Several immune parameters were unaffected by exposure to
m-nitrotoluene, including the
IgG response to sRBC, responses to the B cell
mitogen LPS and to allogeneic cells, and serum
interferon levels. Resistance to Streptococcus pneumoniae and Plasmodium yoelii were unaffected also. Resistance to the
tumor model PYB6 was increased. Exposure of mice to
m-nitrotoluene decreased resistance to Listeria monocytogenes. The decreased resistance to L. monocytogenes may be related to an effect on T cells, evidenced by a decrease in T cell numbers and in the DHR.